Controlled heat transfer with mammalian bodies

ABSTRACT

Methods, computer programming and devices for transferring heat to and/or from a body portion of a mammal are provided. One approach includes directly determining a state of vasoconstriction or vasodilation in a portion of a body, and supplying heat to the portion of the body when vasoconstriction is determined, and removing heat from the portion of the body when vasodilation is determined. The body portion preferably includes specific heat exchange vasculature. In another approach, a transition of the body portion from a state of vasodilation to vasoconstriction is determined and the body portion is then actively kept in a state of vasodilation while removing heat therefrom.

FIELD OF THE INVENTION

The field of this invention relates generally to thermoregulatory statusof mammals, and more particularly to the control and management of heattransfer with mammalian bodies.

BACKGROUND

Mammalian body temperature is normally controlled by an internalautonomic regulatory system referred to herein as the thermoregulatorysystem. One important effector in this system is by controlled by bloodflow to specialized skin areas of the body at non-hairy skin surfaces(i.e., at the palms, soles of the feet, cheeks/nose regions).Subcutaneous to these areas, there are unique anatomical vascularstructures called venous plexuses. These structures serve to deliverlarge volumes of blood adjacent the skin surface. By this delivery ofblood, significant heat transfer is enabled for the maintenance ofinternal organs within a functional temperature range. Blood ispermitted to pass through the venous plexuses “radiator” structures byway of arterio venous anastamosis, or AVAs that gate or control thearterial input side of the venous plexuses. Thus, the AVA's serve anintegral part of the heat transfer system, providing thermoregulatorycontrol. Together, the AVA's and venous plexuses comprise a body'srelevant heat exchange vasculature.

Normally, when body and/or environmental temperatures are high, dilationof certain blood vessels favors high blood flow to the noted heatexchange surfaces, thus increasing heat loss to the environment andreduction in the deep body core region temperature. As environmentaland/or body temperatures fall, vasoconstriction reduces blood flow tothese surfaces and minimizes heat loss to the environment.

There are situations, however, in which it would be desirable tomanipulate the transfer of heat across skin surfaces to lower and/orraise the core body temperature. Such core body cooling or heating wouldbe useful in a number of applications, including therapeutic treatmentregimens and as a component of improving athletic or industrialperformance.

The present invention is geared to improvement implementation of thesegoals. It does so in various ways by specifically taking naturalvasoconstriction tendencies into account in order that unintendedvasoconstriction (during an intended procedure) will not adverselyeffect blood flow in the region of a heat transfer surface so as toprevent adequate heat transfer.

SUMMARY OF THE INVENTION

Methods and devices for manipulating and controlling thethermoregulatory status of a mammal are provided. Software orprogramming for effecting such methodology and running the subjecthardware also forms part of the subject invention.

In one aspect of the invention, a method includes transferring heat toand/or from a body portion of a mammal. The method includes determininga state of vasoconstriction or vasodilation in a portion of a body, andsupplying heat to the portion of the body when and wherevasoconstriction is determined, and removing heat from the portion ofthe body when and where vasodilation is determined. The act ofdetermining vasoconstriction or vasodilation includes sensing acharacteristic of the body associated with the state of vasoconstrictionor vasodilation, (e.g., blood flow rate to the body portion) at the siteof interest, (i.e., where heat transfer it to be effected).

In another aspect of the invention, a transition of the body portionfrom a state of vasodilation to or from vasoconstriction is prompted andthe body portion is then kept in a state of vasodilation while removingheat therefrom. An exemplary method includes inducing a transition ofthe body portion from a state of vasodilation to vasoconstriction byremoving heat from the body portion. A determination of a transitiontemperature associated with the transition from vasodilation tovasoconstriction is then made. Next, the method reestablishesvasodilation in the body portion and removes heat from the body portionat a temperature equal to or greater than the transition temperature. Inanother example, if the body portion is initially in vasoconstriction,heat is supplied until vasodilation occurs in the body portion prior toinducing the transition from vasodilation to vasoconstriction.

The present invention is better understood upon consideration of thedetailed description below in conjunction with the accompanying drawingsand claims.

BRIEF DESCRIPTION OF THE FIGURES

Each of the figures diagrammatically illustrates aspects of theinvention. Of these figures:

FIG. 1 illustrates exemplary system architecture for controlled heattransfer with mammalian bodies;

FIG. 2 illustrates an exemplary hand interface for heat transfer;

FIG. 3 illustrates an exemplary foot interface for heat transfer;

FIGS. 4A–4H illustrate various exemplary configurations ofthermoregulatory sensory manipulation devices;

FIG. 5 illustrates an exemplary control method for heat transfer;

FIG. 6 illustrates an exemplary graph of interface temperature versustemperature gradient;

FIG. 7 illustrates an exemplary graph of interface temperature versusblood flow;

FIG. 8 illustrates an exemplary graph of interface temperature versusblood flow;

FIG. 9 illustrates an exemplary graph of interface temperature versusblood flow including a transition between vasoconstriction andvasodilation;

FIG. 10 illustrates an exemplary graph of interface temperature versusblood flow including a transition between vasoconstriction andvasodilation; and

FIG. 11 illustrates an exemplary graph of interface temperature versusblood flow including a transition between vasoconstriction andvasodilation.

DETAILED DESCRIPTION

Before the present invention is described in detail, it is to beunderstood that this invention is not limited to particular variationsset forth and may, of course, vary. Methods and devices for manipulatingthe thermoregulatory status of a mammal are provided. The followingdescription is presented to enable any person of ordinary skill in theart to make and use the inventions. Descriptions of specific techniquesand applications are provided only as examples. Various modifications tothe examples described herein will be readily apparent to those skilledin the art, and the general principles defined herein may be applied toother examples and applications without departing from the spirit andscope of the invention. Thus, the present invention is not intended tobe limited to the examples described and shown, but is to be accordedthe widest scope consistent with the principles and features disclosedherein.

Methods recited herein may be carried out in any order of the recitedevents which is logically possible, as well as the recited order ofevents—explicit or implied. Furthermore, where a range of values isprovided, it is understood that every intervening value, between theupper and lower limit of that range and any other stated or interveningvalue in that stated range is encompassed within the invention. Also, itis contemplated that any optional feature of the inventive variationsdescribed may be set forth and claimed independently, or in combinationwith any one or more of the features described herein.

All existing subject matter mentioned herein (e.g., publications,patents, patent applications and hardware) is incorporated by referenceherein in its entirety except insofar as the subject matter may conflictwith that of the present invention (in which case what is present hereinshall prevail). The referenced items are provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as an admission that the present invention isnot entitled to antedate such material by virtue of prior invention.

Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin the appended claims, the singular forms “a,” “and,” “said” and “the”include plural referents unless the context clearly dictates otherwise.It is further noted that the claims may be drafted to exclude anyoptional element. As such, this statement is intended to serve asantecedent basis for use of such exclusive terminology as “solely,”“only” and the like in connection with the recitation of claim elements,or use of a “negative” limitation. Unless defined otherwise herein, alltechnical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skill in the art to which thisinvention belongs.

Methodology

Heat transfer from the skin areas of a mammalian body that include heatexchange vasculature, to the outside environment generally occurs whenthe environmental temperature in the area of these body portions is lessthan the temperature of the skin. This temperature difference creates atemperature gradient which drives heat energy from the circulating bloodof the mammalian body to the outside environment, thereby cooling thecore body of the mammal through the circulating blood. However, if thetemperature gradient across the skin surface of these body portions istoo great, the body's natural thermoregulatory system causes the bloodvessels in these areas to constrict, resulting in a reduction in bloodflow and blood circulation to these areas. The reduction in blood flowand blood circulation reduces heat transfer from the core body to theoutside environment via the body portions including AVAs.

As the environmental temperature in contact with the body portionscontaining heat exchange vasculature is gradually decreased, but above atemperature where vasoconstriction occurs, heat transfer away from thebody increases until the vasoconstriction temperature is reached, atwhich point the blood vessels constrict, reducing blood flow to the bodyportion. Generally, heat transfer away from the body decreasessignificantly and suddenly as the temperature falls and triggersvasoconstriction, for example, resulting in a step shaped function ifone were to plot heat transfer or blood flows against temperaturegradient.

In an opposite direction, if the environmental temperature in contactwith the body portion containing heat exchange vasculature is thengradually increased, the blood flow in the area of the body and the heattransfer away from the body increases significantly and suddenly at atemperature higher than the vasoconstriction temperature. It isimportant to note, however, that when the environmental temperature isdecreased and causes vasoconstriction, and then increased and causesvasodilation, that the transition to vasodilation typically occurs at ahigher temperature than the transition to vasoconstriction, such thatthe transition between vasoconstriction and vasodilation is notidentically reversible. Therefore, the transition from vasoconstrictionto vasodilation, and from vasodilation to vasoconstriction, occurs at adifferent temperature range depending on the initial condition(s), aneffect generally referred to as “hysteresis”.

To achieve relatively large heat transfer between the body portioncontaining heat exchange vasculature and the environment, thetemperature of the environment in contact with the body portion isdesirably at a temperature or range of temperatures just above thevasoconstriction temperature of the body portion, i.e., the temperatureassociated with the transition from vasodilation to vasoconstriction.This is the temperature at which the temperature gradient between thebody portion and the environment is greatest and vasoconstriction is notpresent, thereby allowing increased heat transfer from the body core.Such teaching is presented in U.S. patent application Ser. No.09/839,590 entitled Methods and Devices for Extracting Thermal Energyfrom the Body Core of a Mammal. Yet, the application teaches no means ofachieving the desired result outside of applying a thermal medium at aspecified temperature.

In contrast, to effect controlled thermomanipulation in one methodaccording to the invention, in order to determine an optimal heattransfer temperature or temperature range of the environment in contactwith a heat transfer surface of a mammal's body, the temperature atwhich vasoconstriction of the body portion occurs is actuallydetermined. The vasoconstriction temperature can be determined bydecreasing the environmental temperature from a temperature above thevasoconstriction temperature, to a temperature below thevasoconstriction temperature. For example, the vasoconstrictiontemperature can be determined by indirectly or directly detectingvasoconstriction at or near the skin surface while decreasing theenvironmental temperature and noting at which temperature (or range)vasoconstriction occurs. Because the vasodilation temperature isgenerally greater than the vasoconstriction temperature, if theenvironmental temperature is initially below the vasoconstrictiontemperature, the environmental temperature is desirably increased to atemperature above the vasodilation temperature before it is decreased toa temperature below the vasoconstriction temperature to account for thehysteresis effect. The optimal or maximum heat transfer temperature ortemperature range of the environment will be the temperature range justabove the vasoconstriction temperature or the temperature where thetransition to vasoconstriction begins.

Once the optimal heat transfer temperature or temperature range isdetermined, the environmental temperature in contact with the bodyportion containing heat exchange vasculature can be set to or near theoptimal heat transfer temperature to increase heat transfer from thebody to the environment, thus cooling the core body more quickly than athigher or lower temperatures merely representing a guess at an optimaltemperature setting.

Methods and devices for determining and using the optimal heat transfertemperature to cool the core body of mammals are provided in greaterdetail below. In the present methods, the optimal heat transfertemperature is determined, at least in part, on the presence or absenceof vasoconstriction in the area of a body portion containing heatexchange vasculature. The core body temperature of the mammal may thenbe reduced by placing the body portion in an environment at the optimalheat transfer temperature. Further, the temperature wherevasoconstriction occurs and the optimal heat transfer temperature may bereduced by the application of heat to various body portions, or othermeans, to increase the rate of core body cooling. For example, the rateof core body cooling may be increased by the use of negative pressurearound the area of a body portion containing heat exchange vasculaturein order to distend the venous plexuses, thus increasing the bloodvolume available for heat transfer.

Various methods and devices may be used for determining a characteristicassociated with vasoconstriction or vasodilation in a body portion. Inone exemplary method for determining whether a body portion is in avasoconstriction or vasodilation state, the body portion is monitored bymeasuring blood flow in the particular body portion. Normally, when bodyand/or environmental temperatures are high, the dilation of certainblood vessels favors high blood flow to these surfaces, and asenvironmental and/or body temperatures fall, vasoconstriction reducesblood flow to these surfaces and minimizes heat loss to the environment.As such, measuring the blood flow rate in a body portion provides ameasure of whether the body portion is in a state of vasoconstriction orvasodilation.

In one exemplary method for measuring vasoconstriction or vasodilation,blood flow in the body portion is measured and monitored by laserDoppler blood flowmetry. Laser Doppler measurement of the blood flow ina body portion provides a measure of whether the body portion is in astate of vasoconstriction or vasodilation, since changes in blood flowrate are measured. In one example, a laser Doppler imager integratedinto a heat exchange device and directed toward the palm, a finger, orother body portion is used to measure changes in blood flow rate throughthe body portion.

Alternatively, vasoconstriction or vasodilation may be monitored bymeasuring the volume of a body portion. It is commonly understood thatvasodilation coincides with a greater body portion volume than observedduring vasoconstriction owing to increased blood volume within the bodyportion during vasodilation. As such, a physical change in the volume ofa body portion can be correlated to a condition of vasodilation orvasoconstriction. One example of measuring the volume of a body portionwould be to immerse the body portion in a fluid medium. Any changes inthe body portion volume would be registered by a change in the volume offluid medium displaced by the body portion. Or, it may be measured by animpedance-type sensor.

Alternatively, vasoconstriction or vasodilation may be monitored bymeasuring the heat transfer of a body portion. For example, the heattransfer of a body portion is tested by measuring the presence orabsence of a temperature gradient when measuring the temperaturedifference, e.g., between a finger and the corresponding forearm of anarm. The absence of a temperature gradient (indicative of heat transferto the finger) correlates with a condition of vasodilation in thefinger, while a higher temperature in the forearm than in the finger(indicative of no heat transfer to the finger) correlates with acondition of vasoconstriction.

Alternatively, vasoconstriction or vasodilation may be monitored bymeasuring the heat flux at the skin surface. For example, the heat fluxat the skin surface is tested by placing a temperature sensing devicebetween the skin surface and a cooling object in contact with the skin'ssurface. The temperature at this sensing device will indicatevasoconstriction or vasodilation. A temperature higher than that of thecooling object will indicate vasodilation while a temperature close tothat of the cooling object will indicate vasoconstriction because theskin surface will be cooler.

Alternatively, vasoconstriction or vasodilation is monitored bymeasuring light absorption of a portion of the body. For example, lightabsorption can be detected using the technique of plethysmography orthrough use of an infrared pulse oximeter.

Alternatively, vasoconstriction or vasodilation may be monitored bymeasuring the temperature of the body of a mammal. Any convenienttemperature sensing means may be employed, where suitable means includebut are not limited to: thermocouples, thermosistors, microwavetemperature sensors, and the like. The position and nature of thetemperature sensing devices generally depends on the body portion beingtested.

Temperature measurement may involve monitoring the core body temperatureof a mammal. By core body is meant the internal body region or portionof the mammal, as opposed to the surface of the mammal. Specific corebody regions of interest are the core body region of the head, e.g., thedeep brain region, and the core body region of the trunk of the mammal,e.g., the thoracic/abdominal region of the mammal. For detecting thecore body region temperature of the head, sensor locations of interestinclude: the auditory canal (tympanic), the oral cavity, and in the caseof microwave detection, anywhere on the surface of the head to measureunderlying temperature. For detecting thoracic/abdominal core bodytemperature, sensor locations include: the esophagus, the rectum, thebladder, the vagina, and in the case of microwave detection, anywhere onthe surface of the body to measure the underlying temperature.

Alternatively, vasoconstriction or vasodilation may be monitored bymeasuring the skin temperature of a mammal. For detecting the skintemperature of a mammal, the simple empirical nursing methodology ofholding the hand to test for warmth or coldness can be used. Inpracticing this method of skin temperature measurement, a warm hand isgenerally associated with vasodilation, while a cold hand is associatedwith vasoconstriction. The temperature of the skin can also be detectedusing sensors such as thermocouples, thermoresistors, microwavetemperature sensors, temperature sensitive liquid crystals, and othertemperature measuring devices. Placement of temperature sensors on theskin surface could be at the site of heat transfer or other locations,or a combination of locations. In one example, vasoconstriction orvasodilation may be monitored by measuring changes in skin surfacetemperature or heat flow from the body across local skin surface areaoverlying heat exchange vascular structures.

As for these means of monitoring vasoconstriction or vasodilationthrough temperature observation, note-that only detecting temperature atthe location of heat transfer provides a direct measure of localvasoconstriction. However the monitoring is effected (even—forexample—by a combination of any two or more of the above approaches), bycontrolling vasoconstriction or vasodilation in a body portion of amammal, the vasoconstriction temperature and the heat transfertemperature can be lowered to increase the temperature gradient betweenthe area of the body containing heat exchange vasculature and theenvironment, thus increasing heat transfer and facilitating core bodycooling.

In an aspect of the invention, vasoconstriction or vasodilation iscontrolled through thermoregulatory sensory manipulation or “fooling thebrain thermostat.” Certain aspects of such manipulation are provided inU.S. Pat. No. 6,602,277 to Grahn, et al., entitled, “Methods and Devicesfor Manipulating the Themoregulatory Status of a Mammal,” others aspectsare refined herein as will be apparent to one with skill in the art. Allsuch aspects may find use according to the improvements offered byaspects of the present invention.

In any case, it is generally accepted that the brain of a mammal,particularly the Pre-Optic Anterior Hypothalamus (POAH), plays a keyrole in regulating the temperature of body portions in mammals,essentially playing the role of a “thermostat.” In practicing exemplarymethod, heat transfer away from a body portion is achieved bymanipulating the temperature of blood flow to the brain or by changingthe skin temperature of the body (including the head, torso, face, andneck) in order to manipulate (i.e. “fool”) the POAH, by inducing it totrigger vasoconstriction or vasodilation in the body portion allowingcontrolled heat transfer away from the portion. It has further beenappreciated that other stimuli, such as humidity stimulus, may beapplied to the body portion alone or in conjunction with changing theskin temperature.

Manipulating the temperature of blood flow to the brain could beachieved by, for example, thermal wraps around the neck or face. Heatand/or humidity introduced through such wraps is one way to affect thePOAH such that vasodilation is induced and heat transfer away from abody portion such as an arm or leg occurs. Alternatively, humidity maybe applied through such wraps alone or in conjunction with changing theskin temperature.

Alternatively, in practicing the subject method, manipulating thetemperature of blood flow to the brain could be achieved through use ofa suit covering portions of the body and having heating and coolingcomponents and/or humidity controlling components. Exemplary sensorymanipulation devices are described below in greater detail (see, e.g.,FIGS. 4 a–4 h).

Alternatively, vasoconstriction or vasodilation could be controlledthrough application of a surface treatment. For example,vasoconstriction is induced in a body part through topical applicationof Capsaicin (derived from peppers), poison oak, BEN-GAY, a variety ofliniments, a topical irritant, or other suitable chemical and/orbiological materials.

Alternatively, vasoconstriction or vasodilation could be controlledthrough providing one or more pre-selected visual stimuli. In practicingthe subject methods, vasoconstriction could be induced, for example, bytriggering the “fight or flight” response through visual stimulation ofa mammal.

Alternatively, vasoconstriction or vasodilation could be controlledthrough delivery of drugs producing vasoconstriction or vasodilation.For example, drugs may be delivered through injection, inhalation,topically, orally, through the nasal passages, and the like.

In another aspect, heat transfer away from a body portion may befacilitated by applying a negative pressure condition to a portion ofthe body in order to lower the vasoconstriction temperature and/orincrease vasodilation in the body portion. In practicing the exemplarymethods, the negative pressure conditions may be provided using anyconvenient protocol. In many embodiments, the negative pressureconditions are provided by enclosing a body portion of the mammal in asealed enclosure, where the pressure is then reduced in the sealedenclosure thereby providing the desired negative pressure that includesa target heat exchange surface. In many examples of the present methodsand systems, the portion that is sealed includes an arm or leg, or atleast a portion thereof, e.g., a hand or foot. The nature of theenclosure will vary depending on the nature of the appendage to beenclosed, where representative enclosures include gloves, shoes/boots,or sleeves (see, e.g., FIGS. 2 and 3).

Negative pressure includes conditions where a pressure lower thanambient pressure under the particular conditions in which the method isapplied, e.g., 1 ATM at sea level. The magnitude of the decrease inpressure from the ambient pressure under the negative pressureconditions in one example is at least about 20 mmHg, preferably at least30 mmHg, and more preferably at least about 35 mmHg, where the magnitudeof the decrease may be as great as 85 mmHg or greater, but preferablydoes not exceed about 60 mmHg, and more preferably does not exceed about50 mmHg. When the method is performed at or about sea level, thepressure under the negative pressure conditions generally may range fromabout 740 to 675 mmHg, preferably from about 730 to 700 mmHg and morepreferably from about 725 to 710 mmHg.

In practicing the exemplary methods, the negative pressure conditionsduring contact with the skin of a subject may be static/constant orvariable. Thus, in certain examples, the negative pressure is maintainedat a constant value during contact of the surface with the lowtemperature medium. In yet other examples, the negative pressure valueis varied during contact, e.g., oscillated. Where the negative pressureis varied or oscillated, the magnitude of the pressure change during agiven period may be varied and may range from about 85 to 40 mmHg, andpreferably from about 40 to 0 mmHg, with the periodicity of theoscillation ranging from about 0.25 sec to 10 min, and preferably fromabout 1 sec to 10 sec.

Further discussion of suitable vacuum/negative pressure approaches aredescribed in the U.S. Pat. No. 6,602,277 noted above as well as U.S.Pat. No. 5,683,438 to Grahn and PCT Patent Application PCT/US02/09772and U.S. patent application Ser. Nos. 09/839,590 and 09/877,407 toGrahn, et al.—all of which are incorporated herein by reference in theirentireties. Any other details informing the operation of the presentinvention may be drawn from one or more of these four sources, or beprovided by application of the talents of one with ordinary skill in theart.

Embodiments

Turning now to FIG. 1, it illustrates a diagram of an exemplary systemarchitecture for the methods described herein. The exemplary system mayinclude a systems controller 4, pressure source 5, thermal exchangeengine 6, thermoregulatory sensor manipulation device controller 7,sensory manipulation device 8, hand enclosures 2 and 12 includingconductor 1, foot enclosure 13, plumbing and/or electrical connections3, interface specific sensors 10, and body temperature sensors 11.

Systems controller 4 provides and receives signals from the varioussystem components to achieve controlled heat transfer from at least aportion of a body of mammal 9 according to the various methodsdescribed. The systems controller 4 may include a unit having a suitablyprogrammed microprocessor or the like, including algorithms or programlogic for various heating and cooling protocols and schedules asdescribed in detail below. The algorithms may be carried out throughsoftware, hardware, firmware, or any combination thereof. Theprogramming can be recorded on computer readable media, (e.g., anymedium that can be read and accessed directly by a computer). Such mediainclude, but are not limited to: magnetic storage media, such as floppydiscs, hard disc storage medium, and magnetic tape; optical storagemedia such as CD-ROM; electrical storage media such as RAM, ROM, or anEPROM; and hybrids of these categories such as magnetic/optical storagemedia. Any such medium (or other medium) programmed (in full or in part)to operate according to the subject methodology also forms an aspect ofthe invention.

Systems controller 4 is in communication with a thermal exchange engine6, which is capable of heating or cooling a heat exchange medium (notshown) in communication with the conductor 1 located within sealedenclosure 2. The heat exchange medium provided may communicate thermallywith at least a portion of the mammal 9 and with at least a portion ofthe conductor 1. In certain examples, the heat exchange medium iscomprised of a fluid such as water, oil, and the like. In other examplesthe heat exchange medium may include gas or air. In further examples,the heat exchange medium may include solid-state heating or directelectrical heating. Additionally, the systems controller is incommunication with a reservoir (not shown) for containing a supply ofheat exchange medium.

Systems controller 4 is further in communication with a pressure source5 capable of producing negative pressure conditions in the sealedenclosure 2. The thermal exchange engine 6 and the pressure source 5 arein communication with the conductor 1 and the sealed enclosure 2respectively, through plumbing and/or electrical connections 3 capableof conducting heat exchange medium and pressure separately or incombination. The conductor 1 provides an interface between a bodyportion of a mammal 9 and the heat exchange medium in order to heat orcool the body portion of mammal 9. The conductor 1 may include any of anumber of suitable materials for transferring heat. Examples of suchmaterials are metals including, but not limited to, aluminum, stainlesssteel, or titanium. In one example, conductor 1 is disposed withinsealed enclosure 2 in which the body portion is maintained undernegative pressure conditions as described above in detail.

Conductor 1 and sealed enclosure 2 together make up either a handinterface 12 or a foot interface 13. In one example of the presentsystem, the hand interface 12 encloses the arm or hand of mammal 9. Inanother example of the present system, the foot interface 13 enclosesthe leg or foot of mammal 9. In yet another example of the presentsystem, the enclosed body portion includes both arms or hands, both legsor feet, or any combination of the preceding body portions of mammal 9.The hand interface 12 and the foot interface 13 are described below indetail, and shown in FIGS. 2 and 3 respectively.

The systems controller 4 disclosed in FIG. 1 is additionally incommunication with the thermoregulatory sensory manipulation devicecontroller 7 that is further in communication with a thermoregulatorysensory manipulation device 8. The thermoregulatory sensory manipulationdevice 8 is capable of inducing, for example, mild hypothermia forcontrolling a mammal's 9 thermoregulatory response through manipulationof the sensing mechanisms of the brain's (or body's) thermostat.Suitable thermoregulatory sensory manipulation devices may include, butare not limited to, interfaces designed to deliver temperature and/orhumidity stimulus to the following combinations of body portions, someof which are illustrated in FIGS. 4 a–h: the entire body skin surface(FIG. 4 a); head, shoulders, chest, back, torso and arms (FIG. 4 b);head shoulders, chest, back and arms (FIG. 4 c); head shoulders, chestand back (FIG. 4 d); shoulder, chest, back and arms (FIG. 4 e);shoulders, chest, back and torso (FIG. 4 f); chest back torso and legs(FIG. 4 g); torso and legs (FIG. 4 h); head and shoulders; head andneck; head; full face; nose; mouth; nose and mouth; nose and sinuses;and ears. It should be recognized that various other sensorymanipulation devices not shown may be used in accordance with the abovemethods.

Systems controller 4 disclosed in FIG. 1 is additionally incommunication with any of a number of direct or interface specificsensors 10 disposed within or in conjunction with the conductor 1 asdescribed below and shown in detail in FIG. 2. The interface specificsensors 10 provide the systems controller 4 with feedback, e.g.,characteristics associated with vasoconstriction or vasodilation, suchas the relative state of blood flow indicating vasoconstrictionor-vasodilation, of the body portion enclosed. Interface specificsensors 10 may include but are not limited to: laser Doppler blood flowsensing; bio-impedance blood flow sensing; heat flux sensing; interfacetemperature sensing; skin temperature sensing; pressure sensing; bodyportion volume sensing; energy transfer sensing; EKG/ECG or any of themethods disclosed above. Exemplary methods for interpreting and usingfeedback from the interface specific sensors 10 in order to maintain orachieve vasodilation to achieve controlled heat transfer from the bodyof a mammal are provided below.

Systems controller 4 may additionally be in communication with any of anumber of systemic body temperature measuring sensors 11 disposedappropriately on or within the body of the mammal 9. The systemic bodytemperature sensors 11 provide the systems controller 4 with feedbackregarding the core body temperature of the mammal 9, which is desiredfor systems controller 4 to carry out optional portions of exemplarymethods detailed below. The systemic body temperature sensors 11 couldinclude but are not limited to: tympanic temperature sensors; esophagealtemperature sensors; and core body temperature sensors including but notlimited to the methods disclosed above.

FIG. 2 includes a diagram illustrating details of an exemplary handinterface 2-8 that may be used with the system architecture of FIG. 1.The purpose of the hand interface 2-8 includes providing a physical heatexchange surface between the hand of a mammal 2-9 and the conductor 2-1under conditions of negative pressure. The hand interface 2-8 isdesigned to provide temperature and/or humidity stimulus to the hand ofmammal 2-9. Additionally, the hand interface 2-8 enables monitoringand/or manipulation of vasoconstriction or vasodilation through varioussensors that are in communication with the systems controller (FIG. 1).Under the guidance of the systems controller the hand interface 2-8facilitates controlled heat transfer from the body of mammal 2-9.Another exemplary hand interface or module that may be used is describedin U.S. patent application Ser. No. 09/878,129, entitled, “Methods andDevices for Manipulating Thermoregulatory Status of a Mammal,” which ishereby incorporated by reference in its entirety as if fully set forthherein.

The hand interface 2-8 includes a conductor 2-1 that serves as a thermalexchange interface disposed within the sealed enclosure 2-2 and having aconfiguration that accommodates contact between the palm and/or fingersof the mammal 2-9 and the conductor 2-1. The sealed enclosure includes aseal cuff 2-4 and a pressure sensor 2-3 that enables maintenance andmonitoring of negative pressure conditions within enclosure 2-8. Itshould be recognized, however, that an exemplary hand interface 2-8 neednot include an enclosure capable of maintaining a negative pressure. Forexample, hand interface 2-8 may include merely a thermal exchangeinterface or conductor 2-1 for the hand to contact without an enclosure.

The hand interface 2-8 may accommodate any of a number of sensingcomponents. For example, as shown in FIG. 2, a heat flux and interfacetemperature sensor 2-10 can be disposed between the hand of mammal 2-9and the conductor 2-1. Additionally, a laser Doppler or absorbing lightblood flow sensor 2-5 could be disposed within or proximal to theconductor 2-1 for measuring blood flow in the hand of mammal 2-9.Additionally, a heat energy transfer sensor 2-6 could be disposed withinthe conductor 2-1 for measuring the transfer of heat energy between thehand of mammal 2-9 and the conductor 2-1. The hand interface 2-8 couldalso accommodate a skin temperature probe adapted to measure atemperature difference between portions of mammal 2-9 (e.g., a change intemperature from the forearm-to-finger tip), and bio-impedance sensors2-7 as described above for monitoring blood flow in the hand of mammal2-9.

FIG. 3 includes a diagram illustrating details of an exemplary footinterface 3-8 for a foot of mammal 3-9. The foot interface 3-8, likethat of the hand interface described above, provides a physical heatexchange surface between the foot of mammal 3-9 and the conductor 3-1under conditions of negative pressure. The foot interface is designed toprovide temperature and/or humidity stimulus to the foot of a mammal.Additionally, as in the case of the hand interface, the foot interfaceenables monitoring and manipulation of vasoconstriction or vasodilationthrough various sensors that are in communication with the systemscontroller (see, FIG. 1). Under the guidance of the systems controllerthe foot interface facilitates controlled heat transfer from the body ofmammal 3-9.

The foot interface 3-8 includes a conductor 3-1 that serves as a thermalexchange interface disposed within the sealed enclosure 3-2 and having aconfiguration that accommodates contact between the sole of the footand/or toes of the mammal 3-9 with the conductor 3-1. The sealedenclosure includes a sealed cuff 3-4 and a pressure sensor 3-3 thatenable maintenance and/or monitoring of negative pressure conditions asdescribed above. Similar to the hand interface, it should be recognizedthat the exemplary foot interface 3-8 need not include an enclosurecapable of maintaining a negative pressure.

The foot interface 3-8 may accommodate any of a number of sensingcomponents. For example, as shown in FIG. 3, a heat flux and interfacetemperature sensor 3-10 can be disposed between the foot of mammal 3-9and conductor 3-1. Additionally, a laser Doppler or absorbing lightblood flow sensor 3-5 could be disposed within or proximal to theconductor 3-1 for measuring blood flow in the foot of a mammal.Additionally, a heat energy transfer sensor 3-6 could be disposed withinthe conductor for measuring the transfer of heat energy between the footof mammal 3-9 and the conductor 3-1. The foot interface 3-8 could alsoaccommodate a skin temperature probe adapted to measure a temperaturedifference between portions of mammal 3-9 (e.g., a change in temperaturefrom the leg-to-toe tip), and bio-impedance sensors 3-7 for monitoringblood flow in the foot of mammal 3-9 as described above.

In one exemplary method for effecting controlled heat transfer from thebody of a mammal, the driving force includes heat transfer between someportion of the mammal's body, e.g., a skin surface overlying thereferenced heat exchange vasculature, and a thermal interface orconductor (described above and shown in FIGS. 1–3). FIGS. 6–11illustrate more clearly how the exemplary methods and systems describedherein effect an optimal heat transfer from the body core to theenvironment and FIG. 5 illustrates one exemplary method for the systemarchitecture to effectuate increased heat transfer from a mammal. FIG. 6includes a graph depicting a temperature gradient representing thetemperature difference between a mammal's body core temperature(T_(core)) in ° C. and the interface temperature (T_(interface)) in ° C.The Y-axis represents an increasing temperature gradient(T_(core)−T_(interface)) in ° C. while the X-axis represents increasingT_(interface) in ° C. As shown in FIG. 6, when the difference betweenT_(core) and T_(interface) reaches zero (i.e., they are equal) thetemperature gradient no longer exists and heat transfer does not occur(see arrow marking T_(core)). Conversely, the temperature gradientincreases as T_(interface) is increasingly lower than T_(core).

For each individual mammal, vasoconstriction of blood flow within a bodyportion occurs below a certain measurable temperature range whilevasodilation occurs at some point above that temperature range. FIG. 7illustrates this principle by relating increasing levels of blood flowin a body portion on the Y-axis to increasing temperatures ofT_(interface) on the X-axis. As shown in FIG. 7, relatively low bloodflow or vasoconstriction (shown as bar VC below the X-axis) correspondsto a lower range of T_(interface) that extends up to a zone oftransition and culminates in a range of relatively high blood flowcorresponding to vasodilation (shown as bar VD below the X-axis).

One advantage of the exemplary methods and systems described hereinincludes that they relate to both of the foregoing concepts presented inFIGS. 6 and 7. Namely, the systems and methods enable increased heattransfer (T_(Max Heat Transfer)) from the body of a mammal bydetermining the lowest T_(interface) at which vasodilation can bemaintained. As illustrated in FIG. 8, heat transfer can be related as afunction of temperature gradient times blood flow. The graph in FIG. 8superimposes the two graphs of FIGS. 6 and 7 to more clearly illustratethat T_(Max Heat Transfer) occurs at the lowest T_(interface) thatsupports vasodilation, since higher T_(interface) values correlate todiminishing temperature gradients and concomitant reduced coolingeffect.

An additional advantage of the exemplary methods and systems includesthat they address the hysteresis phenomenon generally found in theopposing transitions between vasoconstriction to vasodilation, andvasodilation to vasoconstriction. Disclosed in FIG. 9 is an exemplaryillustration of the phenomenon of hysteresis as it relates to blood flowand T_(interface). FIG. 9 shows increasing blood flow on the Y-axis andT_(interface) on the X-axis to illustrate that the transitions betweenvasoconstriction and vasodilation are not identically reversible withrespect to T_(interface) values. Depending on the initial condition(i.e., vasoconstriction or vasodilation initially) the transition occursat a different temperature range. Particularly, the transition fromvasoconstriction to vasodilation (FIG. 9 plot marked with upwardpointing arrows) occurs at a T_(interface) range that is higher thanthat for the transition from vasodilation to vasoconstriction (FIG. 9plot marked with downward pointing arrows).

With the foregoing as a foundation establishing some of the advantagesand principles relating to the present methods, an exemplary method forheat transfer and controlling a system may now be discussed in greaterdetail. Disclosed in FIG. 5 is a flow chart showing an exemplary methodthat guides the systems controller (described above and shown in FIG. 1)in order to effect controlled heat removal from the body of a mammal. Asystem, e.g., having an appropriately programmed algorithm, programlogic, or the like, begins with a starting value (T_(set)) that equalsthe starting value for T_(interface) (described above). The algorithmmay further include two main components or functions, the first beingfocused on characteristics relating to vasoconstriction and/orvasodilation, e.g., blood flow monitoring and manipulation, and thesecond focused on core body temperature monitoring and manipulation.

The first portion of the method corresponds to the sensing ofvasoconstriction or vasodilation, e.g., by measuring blood flow, andmanipulation of vasoconstriction or vasodilation in a mammal's body partthrough a thermal interface or conductor (e.g., as described above andshown in FIGS. 1–3) in order to establish and maintainT_(Max Heat Transfer) (as described above and shown in FIG. 8).Accordingly, as shown in FIG. 5 generally as 5-1, this aspect of themethod analyzes data regarding the mammal's state of vasoconstriction orvasodilation, and based on this analysis signals for the manipulation ofvasoconstriction or vasodilation or blood flow through incrementallyraising or lowering the T_(set) value (e.g., T_(set)+X⁰; T_(set)−X⁰).

Specifically, in block 5-10, the interface temperature begins at a settemperature, T_(set), which may depend on various factors such as theapplication, body portion, mammal type, and the like. In block 5-12 ameasurement of blood flow or other characteristic associated withvasoconstriction or vasodilation in the body portion is sensed. In block5-14 a determination is then made as to whether the body portion is in astate of vasoconstriction or vasodilation. An initial determination ofvasodilation or vasoconstrictions may be made simply by looking at thecolor of the skin, e.g., on the hand; or by previous measurement ofvasodilation or vasoconstriction using any suitable method for measuringvasoconstriction or vasodilation.

If a determination is made that the body portion is in vasoconstriction,the interface temperature is raised in block 5-16 until vasodilation issensed. The interface temperature, T_(interface), is then lowered inblock 5-18 to a temperature greater than the original set temperature,T_(set), in block 5-10, e.g., X° C. greater. The temperature differencemay vary depending on the application and testing. A characteristicassociated with vasoconstriction or vasodilation is then sensed again inblock 5-12 and a determination made as to vasoconstriction orvasodilation in block 5-14.

If a determination is made that the body portion is in vasodilation, themethod determines if vasoconstriction has been previously sensed inblock 5-20. If not, the interface temperature, T_(set), may be loweredto a temperature below the original set point in block 5-10 and theblood flow or other characteristic sensed again in block 5-12. Ifvasoconstriction has been previously detected, then the method lowersthe interface temperature, T_(set), to a point above the last detectedvasoconstriction temperature.

The second, optional, function of the algorithm may include the sensingof the mammal's core body temperature (discussed above and shown in FIG.1 with regard to body temperature sensors 11) in order to monitor andgovern the process of controlled body core heat removal treatment. Thisfunction of the method is preferably used in situations where it isdesirable to reduce the core body temperature below its normaltemperature and the core body temperature is generally more closelymonitored. As shown in FIG. 5 as 5-2, this function of the algorithmserves to continuously monitor and govern the effect of heat transferaway from the body part(s), which consequently controls body core heatremoval. Particularly, this aspect of the exemplary method takes dataregarding the mammal's core body temperature and compares that value toT_(Max Heat Transfer). Where the core body temperature is found to be ator above the pre-established T_(Max Heat Transfer) for the mammal, themethod provides for treatment to proceed at the present T_(interface)(described above) value. Where the core body temperature is calculatedto be below T_(Max Heat Transfer), the method signals for an increase inT_(interface), and core body temperature data is continuously monitoreduntil it has again reached T_(Max Heat Transfer). This process may berepeated in a cyclic fashion in order to achieve a goal of controlledheat removal treatment over a period of time.

Specifically, with reference to FIG. 5, the exemplary method proceeds toblock 5-26 where the core body temperature is detected by any suitablemethod. If it is below a desired temperature in block 5-28, theinterface temperature is raised in block 5-30. The core body temperaturemay then be determined again and the interface temperature increased ifnecessary.

The methods described in FIG. 5 may be carried out by a controllerhaving a suitable algorithm, program logic, and the like. Alternatively,the exemplary method may be carried out by a person, e.g., a doctor,patient, or the like. Further, the method indicates certain events oroperations occurring in a certain order. In alternative implementations,the order of certain events and operations may be varied, modified, orremoved. Moreover, acts may be added to the described method and stillconform to the described implementations. Further, operations describedherein may occur sequentially or certain operations may occur inparallel.

An advantage of the exemplary methods and systems includes enabling aheat removal treatment from a starting point of vasoconstriction orvasodilation by accounting for the physiological hysteresis phenomenondiscussed above and shown in FIG. 9. For example, FIG. 10 illustrates agraphical representation of the method of FIG. 5 in an instance wherevasodilation is initially detected in the body part of a mammal. In thiscase, from a starting point of vasodilation, the method serves toestablish and maintain T_(Max Heat Transfer) after a condition ofvasodilation is initially detected. An exemplary method or subroutine,e.g. 5-1, accounts for the hysteresis phenomenon attendant to thetransitions between vasoconstriction and vasodilation and initialconditions. According to the hysteresis phenomenon shown in FIG. 9, thevalue of T_(Max Heat Transfer) is lower than the arbitrary value chosenfor T_(set). Specifically, starting with point (A) of FIG. 10, whereblood flow in a body portion indicates a state of vasodilation, thevalue of T_(interface) is arbitrarily made equivalent to T_(set). Thesystem controller then incrementally decreases the value ofT_(interface) below the initial T_(set) value (e.g., T_(set)−X⁰) untilthe transition temperature range between vasoconstriction andvasodilation is passed and vasoconstriction is achieved as shown atpoint (B). The system controller may then increase T_(interface)incrementally above the initial T_(set) value (e.g., T_(set)+X⁰) untilthe transition temperature range between vasoconstriction andvasodilation is reached as shown at point (C). Lastly, the systemcontroller incrementally decreases the value of T_(interface) to thepoint of T_(Max Heat Transfer) as shown at point (D). In summary, thissubroutine provides steps that serve to manipulate a mammal's bodyportion temperature to induce vasoconstriction in order to establish avalue for T_(Max Heat Transfer), followed by re-establishment ofvasodilation through raising the value of T_(interface) to some pointabove T_(Max Heat Transfer) before finally lowering T_(interface) to thepoint of T_(Max Heat Transfer).

FIG. 11 illustrates a graphical representation of the method shown inFIG. 5 for an example where vasoconstriction is initially detected inthe body part of a mammal. As disclosed in FIG. 11, the subjectsubroutine of the algorithm serves to establish and maintainT_(Max Heat Transfer) while taking into account the hysteresisphenomenon attendant to the subject methods (described above and in FIG.9). Specifically, starting at point (A) of FIG. 11, where blood flow ina body portion indicates a state of vasoconstriction, the value ofT_(interface) is arbitrarily made equivalent to T_(set). Next, as shownat point (B), the system controller incrementally increases the value ofT_(interface) above the initial T_(set) value (e.g. T_(set)+X⁰) untilthe transition temperature range between vasoconstriction andvasodilation is reached. When the value of T_(interface) increases abovethe transition temperature range as shown at point (C), vasodilation isachieved. To determine the vasoconstriction temperature, the systemcontroller incrementally decreases the value of T_(interface) untilvasoconstriction occurs as shown at point (D). To account for thehysteresis phenomenon described in FIG. 9, T_(interface) is thenincreased until vasoconstriction is again present as shown at point (E).T_(interface) is then decreased to the point of T as shown at point (F).It should be recognized that when the value chosen for T_(set)corresponds with vasoconstriction initially (as discussed above andshown in FIG. 11), the value of T_(Max Heat Transfer) will be greaterthan the arbitrary value chosen for T_(set). Thus, in summary, theexemplary method serves to manipulate the body portion temperature of amammal by inducing vasodilation through raising the value ofT_(interface) to some point above T_(Max Heat Transfer), lowering theT_(interface) to some point below the vasoconstriction temperature, andagain raising T_(interface) to some point above T_(Max Heat Transfer)before lowering T_(interface) to the point of T_(Max Heat Transfer).

Utility

As demonstrated above, the exemplary methods and systems provide forextracting thermal energy or heat from the core body of a mammal. Assuch, the subject methods are suitable for use in a variety of differentapplications, where representative applications include the treatment ofnormal and abnormal physiological conditions, e.g., disease, where corebody heat extraction is desirable. Representative applications in whichthe subject methods find use include the treatment of exercise or workinduced hypothermia, treatment of stroke, treatment of cystic fibrosissymptoms, treatment of multiple sclerosis symptoms, and the like. Bytreatment is meant at least an alleviation in one or more of thesymptoms associated with the condition being treated, e.g. a reductionin discomfort, amelioration or elimination of symptoms, etc.

In many examples, the subject methods are employed for enhancing theability of a mammal to perform a physical procedure or task. As such,the subject methods are suitable for use in a variety of differentapplications where a variety of different types of physical proceduresare performed. For illustration purposes only, the followingrepresentative applications are provided. However, it should be notedthat the subject methods are suitable for use in the enhancement of thephysical ability of a mammal to perform a plethora of other physicalprocedures not described below.

One type of physical ability that may be enhanced by practicing thesubject methods is athletic ability. In other words, the methods may beused to improve the ability of a mammal to perform an athleticprocedure. The nature of the improvement or enhancement may vary greatlydepending on the nature of the athletic procedure being practiced by themammal. Representative enhancements include, but are not limited to:increases in strength, e.g., as measured by ability to lift a particularweight, etc.; increases in stamina, e.g., as measure in terms of abilityto perform a task or play a sport without resting, etc.; increases inthe ability of the mammal to perform repetitions of a physical task,e.g., weight lifts, pull-ups, etc; decreases in performance limitingafflictions, such as cramps; and the like.

Another type of physical ability that may be enhanced by practicing thesubject methods is physical work ability. In other words, the subjectmethods may be used to improve the ability of a mammal to perform aparticular work related physical procedure. Examples of work relatedphysical procedures include, but are not limited to: physical buildingand maintenance of equipment, particularly in hot environments; buildingand construction, e.g., of homes and offices; civic structure buildingand maintenance, etc; working in a power plant or other industrialenvironment; performing in a military environment, particularly in hotenvironments or with heavy gear; performing in any environment whereheavy gear is required. Enhancement may take many forms including, butnot limited to: increasing the number of repetitive movements that maybe performed; increasing the length of time a particular job may beperformed without resting or cooling; reducing errors in a particularjob; etc.

In many embodiments, the exemplary methods result in more than areduction in recovery time to provide some other enhancement orimprovement, as exemplified above, e.g., enhanced physical ability,increased workout capacity, etc. As mentioned above, the above athleticand work related physical procedures are merely representative of theprocedures that may be enhanced using the subject methods.

Claims

Though the invention has been described in reference to severalexamples, optionally incorporating various features, the invention isnot to be limited to that which is described or indicated ascontemplated with respect to each embodiment or variation of theinvention. It will be apparent to those skilled in the art that numerousmodification and variations within the scope of the present inventionare possible. Thus, the breadth of the present invention is to belimited only by the literal or equitable scope of the followingclaims—not the description provided herein. That being said,

1. A method of transferring heat from a body portion of a mammalcomprising the acts of: determining a state of vasoconstriction orvasodilation in a portion of a body; supplying heat to the portion ofthe body when vasoconstriction is determined; removing heat from theportion of the body when vasodilation is determined, and applyingnegative pressure to the portion of the body.
 2. The method of approach1, wherein the portion of the body is an arterial vascular anastamosiscontaining portion of the body.
 3. The method of approach 1 furtherincluding the act of preselecting the portion of the body.
 4. The methodof approach 1, wherein the act of determining vasoconstriction orvasodilation includes sensing a characteristic of the body associatedwith the state of vasoconstriction or vasodilation.
 5. The method ofapproach 1, wherein the act of determining vasoconstriction orvasodilation includes measuring blood flow.
 6. The method of approach 5,wherein the act of measuring blood flow further includes measuring avolume of the portion of the body.
 7. The method of approach 5, whereinthe act of measuring blood flow further includes measuring blood flow bylaser Doppler.
 8. The method of approach 5, wherein a state ofvasoconstriction is associated with a first range of blood flow levelsand vasodilation is associated with a second range of blood flow levels.9. The method of approach 1, wherein the act of determiningvasoconstriction or vasodilation further includes measuring heattransfer from the portion of the body.
 10. The method of approach 1,wherein the act of determining vasoconstriction or vasodilation furtherincludes measuring the temperature of the body.
 11. The method ofapproach 1, wherein the act of determining vasoconstriction orvasodilation further includes measuring the core body temperature. 12.The method of approach 1, wherein the act of determiningvasoconstriction or vasodilation further includes measuring tympanictemperature.
 13. The method of approach 1, wherein the act ofdetermining vasoconstriction or vasodilation further includes measuringskin temperature of a portion of the body.
 14. The method of approach 1,wherein the act of determining vasoconstriction or vasodilation furtherincludes measuring bio-impedance of a portion of the body.
 15. Themethod of approach 1, wherein the act of determining vasoconstriction orvasodilation further includes measuring light absorption of a portion ofthe body.
 16. The method of approach 1, wherein the act of determiningvasoconstriction or vasodilation further includes providing an EKG. 17.The method of approach 1, wherein the act of determiningvasoconstriction or vasodilation further includes providing an ECG. 18.A method comprising the acts of: monitoring for both vasoconstrictionand vasodilation in a portion of a body; supplying heat to the portionof the body when vasoconstriction is determined; removing heat from theportion of the body when vasodilation is determined; and controlling atleast one of vasoconstriction or vasodilation.
 19. The method ofapproach 18, wherein controlling at least one of vasoconstriction orvasodilation includes the act of inducing vasodilation in a portion ofthe body.
 20. The method of approach 18, wherein controlling at leastone of vasoconstriction or vasodilation includes the act of inducingvasoconstriction in a portion of the body.
 21. The method of approach18, wherein the act of controlling at least one of vasoconstriction orvasodilation includes applying a surface treatment to the portion of thebody.
 22. The method of approach 18, wherein the act of controlling atleast one of vasoconstriction or vasodilation includes influencing thethermoregulatory system of the mammal.
 23. The method of approach 18,wherein the act of controlling at least one of vasoconstriction orvasodilation includes influencing the Pre-Optic Anterior Hypothalamus(POAH) of the mammal.
 24. The method of approach 18, wherein the act ofcontrolling at least one of vasoconstriction or vasodilation includesproviding at least one preselected visual stimulus.
 25. The method ofapproach 18, wherein the act of controlling at least one ofvasoconstriction or vasodilation includes drug delivery.
 26. The methodof approach 18, wherein the act of controlling at least one ofvasoconstriction or vasodilation includes adjusting the temperature ofthe portion of the body.
 27. The method of approach 1, wherein the actof supplying heat further includes supplying sufficient heat to effectvasodilation.
 28. A method of transferring heat from a body portion of amammal comprising the acts of: inducing a transition of a body portionfrom a state of vasodilation to vasoconstriction by removing heat fromthe body portion; determining a transition temperature associated withthe transition from vasodilation to vasoconstriction; reestablishingvasodilation in the body portion; and removing heat from the bodyportion with a temperature equal to or greater than the transitiontemperature.
 29. The method claim 28, wherein if the body portion isinitially in vasoconstriction, supplying heat until vasodilation occursbefore inducing the transition from vasodilation to vasoconstriction.30. The method of claim 28, wherein the temperature is within 2° C. ofthe transition from vasodilation to vasoconstriction.
 31. The method ofclaim 28, wherein the temperature is within 1° C. of the transition fromvasodilation to vasoconstriction.
 32. The method of claim 28, whereinthe temperature is lowered after reestablishing vasodilation withoutinducing vasoconstriction.
 33. A method of transferring heat to or froma portion of a body of a mammal comprising the acts of: determining astate of vasoconstriction or vasodilation in a portion of the body; whenvasodilation is determined, selecting transferring heat to or from theportion of the body; and when vasoconstriction is determined, selectingat least one of supplying heat to the portion of the body and notremoving heat from the portion of the body, whereby optimalthermoregulatory status of the mammal is maintained.
 34. A method forcontrolling the body temperature of a mammal comprising: removing orsupplying heat from a portion of the body, while applying negativepressure to the portion of the body, and maintaining the portion of thebody above a temperature causing vasoconstriction in the portion of thebody by a means for control employing a measured characteristicassociated with a state of vasoconstriction or vasodilation of theportion of the body.
 35. The method of approach 34, wherein thetemperature of the portion of the body is maintained above 18° C. to 22°C.
 36. The method of approach 34, further including the act ofmaintaining the temperature of the portion of the body belowapproximately 25° C.
 37. A method of controlling body temperature of amammal comprising: placing at least a portion of the body in thermalcommunication with a conductor; measuring a characteristic associatedwith a state of vasoconstriction or vasodilation in the portion of thebody; and controlling heating or cooling of the conductor to maintainvasodilation in the portion of the body based upon a value that relatesthe characteristic to vasodilation.
 38. The method of approach 37,wherein the value is determined by supplying heat until vasodilationoccurs, removing heat until vasoconstriction occurs, reestablishingvasodilation, and setting the value equal to or greater than a valuecorresponding to the transition from vasodilation to vasoconstriction.39. The method of approach 38 wherein the value is associated with atemperature of the conductor greater than or equal to a temperaturewhere a transition of vasodialtion to vasoconstriction occurs.
 40. Asystem for controlling body temperature of a mammal comprising: aconductor adapted to interface with a body portion of the mammal; acontroller adapted to vary a temperature of the conductor; a sensorelement for sensing a characteristic associated with vasoconstriction orvasodilation of the body portion, wherein the controller adjusts thetemperature of the conductor to maintain vasodilation in the portion ofthe body portion based upon a predetermined schedule that relates to thecharacteristic to vasodilation.
 41. The system of claim 40, furtherincluding a heat exchange medium in thermal communication with at leasta portion of the mammal and with at least a portion of the conductor.42. A method comprising the acts of: monitoring for bothvasoconstriction and vasodilation in a specific portion of a body;supplying heat to said specific portion of the body whenvasoconstriction is determined; and removing heat from said specificportion of the body when vasodilation is determined.
 43. The method ofapproach 42, wherein the act of determining vasoconstriction orvasodilation includes sensing a characteristic of the body associatedwith the state of vasoconstriction or vasodilation.
 44. The method ofapproach 43, wherein the act of determining vasoconstriction orvasodilation includes measuring blood flow.